Thread-braking device for embroidery machines

ABSTRACT

The present invention relates to a thread-braking device, for in embroidery machines, providing a separate braking unit for each thread feeding the machine, each braking unit being associated with means for adjustment of the braking effect, and common locking means having a central control system.

[111 3,872,812 [451 Mar. 25, 1975 United States Patent [191 Comerio Schoenfeld 1,052,014 2/1913 1,213,344 l/1917 Eggart et a1.

FOREIGN PATENTS OR APPLICATIONS 1 1 THREAD-BRAKING DEVICE FOR EMBROIDERY MACHINES Inventor:

70,605 7/1915 Switzer1and.................,......... 112/83 376,806 4/1907 112/97 255,093 12/1912 Germany.....................,........ 112/97 [73] Assignee:

[22] Filed:

Primary Examiner-George H. Krizmanich Attorney, Agent, or Firm-Al1ison C. Collard, Esq.

52 us. or. 112/255 ABSTRACT [51] Int. D05b 47/00 The pr n inventi n relates to a hread-braking de- [58] Field of Search 112/254, 255, 83, 97 vice, for in embroidery machines, providing a separate braking unit for each thread feeding the machine,

[56] each braking unit being associated with means for ad- References Cited UNITED STATES PATENTS justment of the braking effect, and common locking means having a central control system.

424,620 4/1890 Roy|e....... 1,008,650 11/1911 13 Claims; 6 Drawing Figures THREAD-BRAKING DEVICE FOR EMBROIDERY MACHINES BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a thread-braking device apt to be applied to embroidery machines, and comprising means which operate separately on each thread, to provide a braking action determined according to the conditions and to the type of each thread being braked. A thread-braking device of this type can be used especially in embroidery machines having an automatic change of the ratio and/or of the color, as well as in standard type embroidery machines, thereby providing subatantial advantages in their operation, which turn into better embroidery results.

2. Description of the Prior Art In known machines, thread is fed to each needle by a corresponding reel, and thread advancement is ensured by the traction exerted by the needles themselves. At an intermediate point along the path between the reel and the needles, all the threads pass about a transversal, common braking roller or friction roller, onto which they are wound in one or more turns. This friction roller is mounted freely rotatable on respective bearings, and locking means are further. associated therewith, said means being caused to operate with a pre-established timing in respect of the working cycles.

In practice, operation takes place as follows: each thread is fed, during the forming of a stitch, in that it is drawn by the advancement of the respective needle and by the passage ofa shuttle; since the threads do not slide on the surface of the friction roller, the traction effect exerted by the threads of all the needles, or of at least a large part of the needles, is sufficient to draw or turn the friction roller, being idle, which thus performs a short rotation.

At the moment when stitch knotting is carried out, for which the threads have to be pulled backwards for the forming and closing of the stitches, it is instead indispensable to stop the feeding of the threads. For this purpose, the aforementioned locking means are momentarily operated, stopping the friction roller from rotating: the friction produced between the surface of this roller and each thread, is then sufficient particu- 'larly when the threads are wound in several turns about form feeding conditions, also when the resistance of the individual thread feeding reels in unwinding is different from reel to reel, for example due to non-uniform weight or size, that is with more or less worn and hence more or less heavy reels.

This known device nonetheless has a drawback: the friction roller has a considerable mass and thus has a certain inertia, whereby sutstantial force is required to bring it into rotation at the moment when feeding any of the threads. If all the needles are at work, and hence all the threads exert a traction on the roller, the total effect of the traction forces produced by them is sufficiently high. If however only a few needles are at work as when special operations are carried out with very high ratios in order to obtain the same total traction effect, the threads have to exert an exceedingly high traction force in the friction roller so that their feeding is constantly and exceedingly braked which creates dif-. ficulties in the working.

In this case, one is compelled tto prevent the winding of the single threads around the friction roller and to resort to emergency braking means, for example by winding the threads around fixed pivots. The result is, however, that the braking intensity on the individual threads then varies according to theinertia, namely the weight, of the respective feeding reels. Moveover, if the friction roller is no longer used, there will also be no more possibility of locking the thread when knotting the stitch, so that there are further difficulties.

The above drawbacks are felt even more in the case of machines with ratio and/or color chanbe, in which some of the individually selected needles have to staty out of work, and hence the corresponding thread feed must be stopped; this is of course impossible if the threads are wound onto a common feeding roller, such as the above mentioned friction roller.

SUMMARY OF THE INVENTION All the above drawbacks are eliminated by the braking device according to the present invention, being characterized in that it comprises a separate braking unit for each needle of the machine, each braking unit being associated with means for adjustment of the braking effect, and common locking means having a central control system.

In other words, the basic idea of the present invention is to provide a braking unit in association with each thread, that is each needle, and to obtain in each braking unit a separation of the braking function during feeding from the locking function during knotting. It is thus possible to adjust, the braking effect for each thread separately (for example accordingto the type of thread,'to the inertia of the respective reel, or some other factor), while locking is performed by a central control system, acting simultaneously on all the braking units.

According to a first embodiment, this result is obtained in that a braking effect is obtained in each braking unit by a flexible lamina, integral at one end with a support bracket and carrying at the other end a braking shoe which imparts an adjustable pressure to a thread, while a locking function is performed by a pair of pads, between which slides the thread, at least one of the pads being movable so as to be pushed closer to and tightened against the other in order to lock the thread.

According to a, preferred embodiment, each braking unit comprises a freely rotatable friction roller on which the thread is wound in at least one turn, the braking adjustment means consisting of adjustable friction means contacting the roller periphery, hence braking the rotation thereof, while said lockingmeans consist of a pawl device for stopping the roller itself.

BRIEF DESCRIPTION OF THE DRAWINGS The invention is now being described with reference to preferred embodiments, given by way of example, which are illustrated in the accompanying drawings, wherein: I

FIG. 1 is a schematic, partial, front view of an exemplary device according to the invention, comprising two braking units;

FIGS. 2 and 3 are, respectively, a schematic, partial plan view of the same device, with elements removed,

and a schematic, partial, side view partially sectioned; and

FIGS. 4, and 6 are similar views to those of FIGS. 1, 2 and 3 respectively, of a preferred embodiment of the device according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the drawings, lines A, B indicate trajectories of two exemplary threads feeding the needles of a machine; for the sake of simplicity, only these two trajectories are indicated, and it should be understood that the inventive braking units are repeated in a number equal to the number of the needles.

According to the exemplary embodiment illustrated in FIGS. 1 to 3, each braking unit comprises a support bracket 1 on which are mounted both the braking adjustment means and the common locking means. All

the support brackets I are fixed onto a common bar 2 end a shoe of a material having suitable sliding characteristics, forexample'of steel. Opposite to the shoe 6 is provided a flat surface 7 of the support 1 itself.

More or less at the center of the lamina 5 acts a setscrew 8, with a knurled peripheral surface, and by acting manually on the set screw, it is possible to produce flexion of the lamina 5 and to cause the shoe 6 to press against the surface 7 with a higher or lower pressure.

Between the shoes 6 and the surfaces 7 slide the threads A, B, which are hence subjected to a continuous braking action, the value of which varies according to the pressure with which the shoe 6 bears onto the surface 7, the pressure being determined by the action of the setscrews 8 on the laminae 5.

Equally on the trajectory of the threads A, B, are arranged pairs of stopping pads 9, 10 in each braking unit. The pad 9 is integral with the support 1, while the pad 10 is carried by a small cylinder 11 (FIG. 1). The latter is in turn mounted sliding within a seat 12a of an operating arm 12 against the reaction of a spring 13 and guided by a rod 14. Movement of the cylinder 11 is allowed in a direction perpendicular to the sliding direction of the thread.

All the operating arms 12 of the braking units, are in turn mounted on a common control bar 15, each in a position adjustable by means of a screw 16. The bar 15 is movable axially on supports 17 of the machine frame.

Operation is as follows. First of all, at the moment in which a new reel is mounted on the machine, for example for the needle A, its thread is caused to slide between the shoe 6 and the surface 7, and between the pads 9, 10; the thread follows the path indicated with the dash-and-dot line A in FIG. 3. Then, the pressure of the shoe 6 is adjusted by means of the screw 8 according to the desired continuous braking effect on the thread, taking into account quality, section, weight of the thread. and any other working condition.

The pressure may be adjusted at the beginning of the operation and of the reel, and may be readjusted during the operation itself, as the reel runs out, so as to take into account not only the characteristics of the thread but also the weight of the reel, and hence'its inertia to unwinding.

While the needle is advances, in operation, or during the shuttle passage, the threads A, B, can slide between the shoes 6 and the surfaces 7, slightly braked according to the working requirements. At the moment in which knotting is carried out, the bar 15 is abruptly displaced by a short stroke in the direction of the arrow F (FIG. 1). With this movement, the arms 12 are also displaced in the direction F, thus driving the pads 10 against the corresponding pads 9. Their pressure is determined by the action of the spring 13 which, in this movement, is momentarily compressed. This pressure of one pad against the other is sufficient to lock the thread tightly, thus preventing any sliding thereof during the stitch knotting operation. It should be noted that this arrangement makes for a stepwise movement of the threads.

As soon as the knotting has been carried out, the bar 15 is moved backwards, and returns in the position shown, for free thread feeding.

In the second, preferred embodiment shown in FIGS. 4 to 6, each braking unit comprises a braking roller 21 for each needle of the machine, that is for each thread, the surface of which roller has good frictional characteristics in respect of the threads used in the embroidery machine. In practice, each roller 21 may be formed like a short section of a braking friction roller of the abovementioned known type. All the rollers 21 are mounted freely rotatable on a common, stationary, support shaft 22.

Starting from a reel 23, each feeding thread A is wound in one or more turns onto its roller 21, and from the latter it then moves towards the respective needle on the embroidery machine needle frame, advancing according to an arrow A.

Parallel to the support shaft 22 is further provided a first secondary shaft 25, on which are mounted several rings 26, namely one ring 26 for each braking unit. Such rings are keyed on the shaft 25 by means of screws 26a, which also allow to adjust the position of the ring 26 in respect of the shaft 25.

A flexible lamina 27 is integral with each ring 26, being fixed for example by welding or being set in, said laminae bearing with their free ends against the peripheries of the rollers 21. The pressure with which each lamina 27 bears against the roller 21 determines the desired braking effect on the roller itself. This pressure is first of all adjustable separately by adjusting, as said, the position of the ring 26 on the shaft 25, and further by adjusting the angular position of the shaft 25 itself: rotation in the direction of an arrow F increases the pressure while rotation in the direction of an arrow F reduces the pressure.

Parallel to the shafts 22 and 25 is further provided a secondary shaft 28 on which is mounted a plurality of pawl arms or rods 29, (see FIG. 5) by means of respective securing screws 29a; the number of rods 29 is equal to the number of needles, that is of the braking units. The shaft 28 with the resilient pawl arms 29 constitutes common locking means. Each arm 29 ends in a hook portion 29b engaging the teeth of the roller 21, namely with one of peripheral teeth 30 of the latter.

In the position illustrated in FIG. 6, the pawl ends of the rods 29 engages the just mentioned peripheral teeth (toothed rings) 30 integral with the rollers 21, in such a way as to prevent their anticlockwise rotation (in respect of the drawing). Through oscillation of the shaft 28 in the direction of an arrow F it is possible to disengage the pawl end (hooks 29b) from the teeth 30, thus freeing the rollers 21, while re-engagement can be operated by rotation in the direction of an arrow F The operation of the above described device takes place as follows, explained for a single braking unit of the device. During needle advancement and penetration through the fabric, as during the forming of a hole for the shuttle passage, each thread corresponding to a needle at work is moved in the feeding direction A (FIG. 6) so that it in turn draws the corresponding roller 21 into anticlockwise rotation; this rotation is regularly braked by the lamina 27. Actually, the rotation of the roller 21 is free in that the hook 29b of pawl 29 is disengaged from the teeth 30.

At the moment in which stitch knotting is carried out, when it is instead necessary to prevent thread feeding, the pawl 29 starts to operate and is caused to rotate anti-clockwise according to arrow F hence engaging the teeth 30 and stopping the roller 21 from rotating. This provides the necessary intermittent or stepwise thread feed required in these machines. The friction surface of the roller 21 covered for example with emery, rubber or some other anti-slide material, then firmly keeps the thread, thanks also to the fact thatthe thread is wound around it into several turns.

Since all the laminae 27 are keyed onto the shaft 25 and since all thepawls 29 are keyed onto the shaft 28, it is possible to operate simultaneously, in correspon dence of all the needles, not only the pawls 29, that is the locking of all the threads, but also the pressure adjustment of the laminae 27.

It is understood that the invention should not be considered as limited to the particular embodiments described but that there may be several other embodiments different from the above, without thereby departing from the scope of the present invention.

It should in fact be noted, in particular, that the single and simultaneous central control system for the locking means has been indicated essentially for the purposes of economy, but that, for example, the locking move ment may be achieved through known electromagnetic controls separately on the rods 14 of the pads (first embodiment) or on the pawl arms 29 (second). The advantage provided by such controls is that they can be operated selectively, should the neecessity arise, on machines with an automatic change of the ratio and/or of the color.

I claim:

1. A thread-braking device for embroidery machines having a plurality of threads fed in a stepwise manner, the device comprising a separate braking unit associated with each thread being fed to the machine, means for adjusting the braking effect in said braking units, and common locking means for the threads.

2. The device as defined in claim 1, further comprising means for independently adjusting the braking effect in each of said braking units.

3. Device as in claim 2, in which said braking adjustment means comprise a resilient lamina, being integral at one end with a respective support bracket and carrying at the other end a braking shoe with adjustable pressure.

4. Device as in claim 3, in which a setscrew is associated to said lamina, said setscrew being apt to bend the lamina and a respective shoe towards a corresponding opposite surface, between said surface and said show sliding the feeding thread. i

5. Device as in claim 1, in which said locking means comprise a pair of normally spaced pads, between which freely slides the thread, at least one of the said pads being movable against the other so as to tighten and lock the feeding thread sliding between them.

6. Device as in claim 5, wherein one of said pads is integral with a respective fixed support bracket, and the other pad is integral with a small operating cylinder, sliding perpendicularly toward the thread feeding directlon.

7. Device as in claim 6, in which said operating cylinder is mounted slidingly within a seatof a respective operating arm, against the action of a compression spring.

8. Device as in claim 7, in which said operating arms, relative to all the braking devices, are integral with a controlbar perpendicularly movable toward the thread feeding direction.

9. A thread-braking-device for embroidery machines having a plurality of threads fed in a stepwise manner, the device comprising a separate braking unit associated with each thread being fed to the machine, each of said units including a braking roller on which the respective thread is wound in at least one turn, a common shaft on which said rollers are mounted in a freely rotatable manner, means for adjusting the braking effect in each of said braking units, and common locking means for the threads.

10. The device as defined in claim 9, wherein each of said braking adjusting means includes a flexible lamina frictionally bearing with one of its free ends, with an ad justable pressure, against the periphery of the respective one of said braking rollers.

11. The device as defined claim 10, wherein said laminae are mounted on a first secondary shaft, by the intermediary of position regulating means, parallel to said common shaft, said first shaft being in turn adjustably mounted so as to be rotatable about its own axis.

12. The device as defined in claim 9, wherein said locking means includes apawl arm for engaging corresponding peripheral teeth integral with each of said braking rollers.

13. The device as defined in claim 12, wherein said pawl arms are mounted on a second secondary shaft, parallel to said common shaft, said second shaft being respectively movable, by way of rotation about its own axis, into a locking position in which the ends of said pawl arms engage said teeth, and into a releasing position in which said pawl-arm ends are spaced away from 

1. A thread-braking device for embroidery machines having a plurality of threads fed in a stepwise manner, the device comprising a separate braking unit associated with each thread being fed to the machine, means for adjusting the braking effect in said braking units, and common locking means for the threads.
 2. The device as defined in claim 1, further comprising means for independently adjusting the braking effect in each of said braking units.
 3. Device as in claim 2, in which said braking adjustment means comprise a resilient lamina, being integral at one end with a respective support bracket and carrying at the other end a braking shoe with adjustable pressure.
 4. Device as in claim 3, in which a setscrew is associated to said lamina, said setscrew being apt to bend the lamina and a respective shoe towards a corresponding opposite surface, between said surface and said show sliding the feeding thread.
 5. Device as in claim 1, in which said locking means comprise a pair of normally spaced pads, between which freely slides the thread, at least one of the said pads being movable against the other so as to tighten and lock the feeding thread sliding between them.
 6. Device as in claim 5, wherein one of said pads is integral with a respective fixed support bracket, and the other pad is integral with a small operating cylinder, sliding perpendicularly toward the thread feeding direction.
 7. Device as in claim 6, in which said operating cylinder is mounted slidingly within a seat of a respective operating arm, against the action of a compression spring.
 8. Device as in claim 7, in which said operating arms, relative to all the braking devices, are integral with a control bar perpendicularly movable toward the thread feeding direction.
 9. A thread-braking device for embroidery machines having a plurality of threads fed in a stepwise manner, the device comprising a separate braking unit associated with each thread being fed to the machine, each of said units including a braking roller on which the respective thread is wound in at least one turn, a common shaft on which said rollers are mounted in a freely rotatable manner, means for adjusting the braking effect in each of said braking units, and common locking means for the threads.
 10. The device as defined in claim 9, wherein each of said braking adjusting means includes a flexible lamina frictionally bearing with one of its free ends, with an adjustable pressure, against the periphery of the respective one of said braking rollers.
 11. The device as defined claim 10, wherein said laminae are mounted on a first secondary shaft, by the intermediary of position regulating means, parallel to said common shaft, said first shaft being in turn adjustably mounted so as to be rotatable about its own axis.
 12. The device as defined in claim 9, wherein said locking means includes a pawl arm for engaging corresponding peripheral teeth integral with each of said braking rollers.
 13. The device as defined in claim 12, wherein said pawl arms are mounted on a second secondary shaft, parallel to said common shaft, said sEcond shaft being respectively movable, by way of rotation about its own axis, into a locking position in which the ends of said pawl arms engage said teeth, and into a releasing position in which said pawl-arm ends are spaced away from said teeth. 